Machines, including track-type tractors, wheel loaders, haul trucks, and other construction and mining equipment, are used for a variety of tasks. In order to accomplish these tasks, the machines typically include an internal combustion engine such as a diesel engine, gasoline engine, or gaseous fuel-powered engine that produces significant amounts of power by combusting a fuel/air mixture. This combustion process generates large amounts of heat. In order to ensure proper and efficient operation of the engine, a cooling system is required to cool fluids directed into or out of the engine.
For example, an internal combustion engine is generally fluidly connected to several different liquid-to-air and/or air-to air heat exchangers to cool both liquids and gases circulated throughout the engine. These heat exchangers are often located close together and/or close to the engine to conserve space on the machine. A fan is disposed either in front of the engine/exchanger package to blow air across the exchangers and the engine, or between the exchangers and engine to suck air past the exchangers and blow air past the engine.
The size of the engine and power output of the engine may be at least partially dependent on the amount of cooling provided to the engine. That is, the engine may have a maximum temperature and a most efficient operating temperature range. Operation of the engine may be limited by the capacity of the associated exchangers to maintain the engine's temperatures below the maximum limit and within the optimum range. In addition, given the space constraints of a particular engine's enclosure, the size of the exchangers may also be limited. Therefore, it becomes necessary to maximize cooling efficiency for a given space constraint.
Maximizing cooling efficiency can be difficult, especially when multiple engine and non-engine heat exchangers are packaged together. That is, in some configurations, air-to-air after coolers (ATAAC) are co-located with engine heat exchangers to take advantage of the airflow generated by the fan. In these situations, the heat transfer from the ATAACs can affect the heat transfer from the engine's exchangers, as well as consume space within the engine's compartment.
One attempt to maximize machine cooling within a given engine compartment is disclosed in U.S. Pat. No. 7,228,885 (the '885 patent), issued to Kolb et al. on Jun. 12, 2007. The '885 patent describes a heat exchanger package for an engine system. The heat exchanger package includes a radiator having upper and lower portions for cooling engine coolant and a charge air cooler having upper and lower portions for cooling charge air. The upper charge air cooler portion is disposed adjacent to and overlapping the upper radiator portion. In addition, the lower charge air cooler portion is disposed adjacent to and overlapping the lower radiator portion. Furthermore, the upper charge air cooler portion and the lower radiator portion are aligned in a first plane, while the upper radiator portion and the lower charger air cooler portion are aligned in a second plane behind the first plane. Ambient cooling air flows in series through the upper charge air cooler portion and the upper radiator portion and in series through the lower charge air cooler portion and the lower radiator portion.
Although the cooling system of the '885 patent may provide a compact heat exchanger package, the efficiency and cooling capacity may be limited. In particular, the cooling system does not account for the changing relationship between the radiator and charge air heat loads of different engine operating conditions. For example, during some engine operating conditions, the radiator and charge air heat load may increase or decrease together. In other engine operating modes, the radiator and charge air heat loads may increase or decrease independently. Therefore, the '885 cooling system, may be efficient under certain engine operating conditions and inefficient under others.
The disclosed cooling system is directed to overcoming one or more of the problems set forth above.